From nobody Sat Feb 7 08:02:37 2026 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 970BE45106C for ; Wed, 21 Jan 2026 22:40:24 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769035230; cv=none; b=Zn4yL8NwVF2fIpmQcvn8FJ3vBT/eKQ7TI6shn8IOGtcZS1HktmYprKsIinK1YWVY1kMqi3r6ZddGQsgh1YsG+h7zvhsQYj/YZz2/JXIhBLUEzVjzEp21ZmdVpd/gMeJB+RKd0MSnxNSWvKmWtOCYGyJ5SCaeEy6HQot1zvxkgCU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769035230; c=relaxed/simple; bh=aMHa2HGGjDOqvxNGsC1lkpfOeKMP2D4ZncGOR+AC454=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=PB41+/sglwiPRa2dlWNphmqOcPW0euO8vB8rri1TWFNEyCh8DEUgRxoSqyLHLfDmwNjYatFDsIwmOatJv0VCzqANWWwFgjbeXiFnapdfROcFliGEviGpnNSfx/I79aw0Jwal5olHCQlMmYF3pMg/yYPZMeNH80t6nyttVJQ9muQ= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=egG4Qg4m; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="egG4Qg4m" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1769035221; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=vtCmgDZXO0My+mI7rD1MZ69sKZN8gNruwxqfmc5tCc8=; b=egG4Qg4mtZYWLute6N+NDySQLbTXC97nbrWywBscmM5vbq2pQT0HLyrwc2Pf1K6MvOK8w0 ESLhl1QROOYXlfrm47w58mtEycYUQb/6wsMSrtEJ7lEZ6EQXxkGAVkA4LoUv4yn2U3tzo4 01P+8ZM9HNZuePjMRjQUNQf923+CLM8= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-665-Ec_XDxH_MoK92gwWsHsKag-1; Wed, 21 Jan 2026 17:40:17 -0500 X-MC-Unique: Ec_XDxH_MoK92gwWsHsKag-1 X-Mimecast-MFC-AGG-ID: Ec_XDxH_MoK92gwWsHsKag_1769035214 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B17C51955F28; Wed, 21 Jan 2026 22:40:14 +0000 (UTC) Received: from GoldenWind.redhat.com (unknown [10.22.89.232]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6502319560AB; Wed, 21 Jan 2026 22:40:11 +0000 (UTC) From: Lyude Paul To: rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner Cc: Boqun Feng , Daniel Almeida , Miguel Ojeda , Alex Gaynor , Gary Guo , =?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Andrew Morton , Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long Subject: [PATCH v17 07/16] rust: Introduce interrupt module Date: Wed, 21 Jan 2026 17:39:10 -0500 Message-ID: <20260121223933.1568682-8-lyude@redhat.com> In-Reply-To: <20260121223933.1568682-1-lyude@redhat.com> References: <20260121223933.1568682-1-lyude@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 This introduces a module for dealing with interrupt-disabled contexts, including the ability to enable and disable interrupts along with the ability to annotate functions as expecting that IRQs are already disabled on the local CPU. [Boqun: This is based on Lyude's work on interrupt disable abstraction, I port to the new local_interrupt_disable() mechanism to make it work as a guard type. I cannot even take the credit of this design, since Lyude also brought up the same idea in zulip. Anyway, this is only for POC purpose, and of course all bugs are mine] Signed-off-by: Lyude Paul Co-developed-by: Boqun Feng Signed-off-by: Boqun Feng Reviewed-by: Benno Lossin Reviewed-by: Andreas Hindborg --- V10: * Fix documentation typos V11: * Get rid of unneeded `use bindings;` * Move ASSUME_DISABLED into assume_disabled() * Confirm using lockdep_assert_irqs_disabled() that local interrupts are in fact disabled when LocalInterruptDisabled::assume_disabled() is called. rust/helpers/helpers.c | 1 + rust/helpers/interrupt.c | 18 +++++++++ rust/helpers/sync.c | 5 +++ rust/kernel/interrupt.rs | 86 ++++++++++++++++++++++++++++++++++++++++ rust/kernel/lib.rs | 1 + 5 files changed, 111 insertions(+) create mode 100644 rust/helpers/interrupt.c create mode 100644 rust/kernel/interrupt.rs diff --git a/rust/helpers/helpers.c b/rust/helpers/helpers.c index 79c72762ad9c4..f97d1cb63e0cd 100644 --- a/rust/helpers/helpers.c +++ b/rust/helpers/helpers.c @@ -29,6 +29,7 @@ #include "err.c" #include "irq.c" #include "fs.c" +#include "interrupt.c" #include "io.c" #include "jump_label.c" #include "kunit.c" diff --git a/rust/helpers/interrupt.c b/rust/helpers/interrupt.c new file mode 100644 index 0000000000000..f2380dd461ca5 --- /dev/null +++ b/rust/helpers/interrupt.c @@ -0,0 +1,18 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +void rust_helper_local_interrupt_disable(void) +{ + local_interrupt_disable(); +} + +void rust_helper_local_interrupt_enable(void) +{ + local_interrupt_enable(); +} + +bool rust_helper_irqs_disabled(void) +{ + return irqs_disabled(); +} diff --git a/rust/helpers/sync.c b/rust/helpers/sync.c index ff7e68b488101..45b2f519f4e2e 100644 --- a/rust/helpers/sync.c +++ b/rust/helpers/sync.c @@ -11,3 +11,8 @@ void rust_helper_lockdep_unregister_key(struct lock_class= _key *k) { lockdep_unregister_key(k); } + +void rust_helper_lockdep_assert_irqs_disabled(void) +{ + lockdep_assert_irqs_disabled(); +} diff --git a/rust/kernel/interrupt.rs b/rust/kernel/interrupt.rs new file mode 100644 index 0000000000000..6c8d2f58bca70 --- /dev/null +++ b/rust/kernel/interrupt.rs @@ -0,0 +1,86 @@ +// SPDX-License-Identifier: GPL-2.0 + +//! Interrupt controls +//! +//! This module allows Rust code to annotate areas of code where local pro= cessor interrupts should +//! be disabled, along with actually disabling local processor interrupts. +//! +//! # =E2=9A=A0=EF=B8=8F Warning! =E2=9A=A0=EF=B8=8F +//! +//! The usage of this module can be more complicated than meets the eye, e= specially surrounding +//! [preemptible kernels]. It's recommended to take care when using the fu= nctions and types defined +//! here and familiarize yourself with the various documentation we have b= efore using them, along +//! with the various documents we link to here. +//! +//! # Reading material +//! +//! - [Software interrupts and realtime (LWN)](https://lwn.net/Articles/52= 0076) +//! +//! [preemptible kernels]: https://www.kernel.org/doc/html/latest/locking/= preempt-locking.html + +use kernel::types::NotThreadSafe; + +/// A guard that represents local processor interrupt disablement on preem= ptible kernels. +/// +/// [`LocalInterruptDisabled`] is a guard type that represents that local = processor interrupts have +/// been disabled on a preemptible kernel. +/// +/// Certain functions take an immutable reference of [`LocalInterruptDisab= led`] in order to require +/// that they may only be run in local-interrupt-disabled contexts on pree= mptible kernels. +/// +/// This is a marker type; it has no size, and is simply used as a compile= -time guarantee that local +/// processor interrupts are disabled on preemptible kernels. Note that no= guarantees about the +/// state of interrupts are made by this type on non-preemptible kernels. +/// +/// # Invariants +/// +/// Local processor interrupts are disabled on preemptible kernels for as = long as an object of this +/// type exists. +pub struct LocalInterruptDisabled(NotThreadSafe); + +/// Disable local processor interrupts on a preemptible kernel. +/// +/// This function disables local processor interrupts on a preemptible ker= nel, and returns a +/// [`LocalInterruptDisabled`] token as proof of this. On non-preemptible = kernels, this function is +/// a no-op. +/// +/// **Usage of this function is discouraged** unless you are absolutely su= re you know what you are +/// doing, as kernel interfaces for rust that deal with interrupt state wi= ll typically handle local +/// processor interrupt state management on their own and managing this by= hand is quite error +/// prone. +pub fn local_interrupt_disable() -> LocalInterruptDisabled { + // SAFETY: It's always safe to call `local_interrupt_disable()`. + unsafe { bindings::local_interrupt_disable() }; + + LocalInterruptDisabled(NotThreadSafe) +} + +impl Drop for LocalInterruptDisabled { + fn drop(&mut self) { + // SAFETY: Per type invariants, a `local_interrupt_disable()` must= be called to create this + // object, hence call the corresponding `local_interrupt_enable()`= is safe. + unsafe { bindings::local_interrupt_enable() }; + } +} + +impl LocalInterruptDisabled { + /// Assume that local processor interrupts are disabled on preemptible= kernels. + /// + /// This can be used for annotating code that is known to be run in co= ntexts where local + /// processor interrupts are disabled on preemptible kernels. It makes= no changes to the local + /// interrupt state on its own. + /// + /// # Safety + /// + /// For the whole life `'a`, local interrupts must be disabled on pree= mptible kernels. This + /// could be a context like for example, an interrupt handler. + pub unsafe fn assume_disabled<'a>() -> &'a LocalInterruptDisabled { + const ASSUME_DISABLED: &LocalInterruptDisabled =3D &LocalInterrupt= Disabled(NotThreadSafe); + + // Confirm they're actually disabled if lockdep is available + // SAFETY: It's always safe to call `lockdep_assert_irqs_disabled(= )` + unsafe { bindings::lockdep_assert_irqs_disabled() }; + + ASSUME_DISABLED + } +} diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs index f812cf1200428..fbe830c4c54e4 100644 --- a/rust/kernel/lib.rs +++ b/rust/kernel/lib.rs @@ -101,6 +101,7 @@ pub mod i2c; pub mod id_pool; pub mod init; +pub mod interrupt; pub mod io; pub mod ioctl; pub mod iov; --=20 2.52.0